Window Ratings
From Zissil
Warning: You are not logged in.
Your IP address will be recorded in this page's edit history.The edit can be undone.
Please check the comparison below to verify that this is what you want to do, and then save the changes below to finish undoing the edit.
Latest revision | Your text | ||
Line 8: | Line 8: | ||
|data8 = Various ratings used to determine the energy efficiency of replacement windows.}} | |data8 = Various ratings used to determine the energy efficiency of replacement windows.}} | ||
− | + | Consumers can assess a window's thermal performance by the '''window's qualifying ratings'''. Initial costs of an energy efficient window is offset, over the course of the window's life, by a better insulated home and lower energy bills. | |
== Window Ratings == | == Window Ratings == | ||
Homeowners who want to purchase [[Energy Efficient Windows|energy efficient replacement windows]] can assess the window's energy efficiency by reviewing the window's ratings. The United States Department of Energy and the Environment Protection Agency accept the ratings that are provided by the [[National Fenestration Ratings Council|National Fenestration Ratings Council]]. | Homeowners who want to purchase [[Energy Efficient Windows|energy efficient replacement windows]] can assess the window's energy efficiency by reviewing the window's ratings. The United States Department of Energy and the Environment Protection Agency accept the ratings that are provided by the [[National Fenestration Ratings Council|National Fenestration Ratings Council]]. | ||
− | The NFRC's ratings appear on the Energy Star label. Energy Star windows are frequently eligible for [[Replacement-Window-Tax-Credits-and-Rebates|tax credits and other rebates]], depending on the region in which the windows are to be installed. The NFRC also rates components of the window that are not included in Energy Star qualifications. | + | The NFRC's ratings appear on the Energy Star label. Energy Star windows are frequently eligible for [[Replacement-Window-Tax-Credits-and-Rebates|tax credits and other rebates]], depending on the region in which the windows are to be installed. The NFRC also rates components of the window that are not included in Energy Star qualifications. |
− | + | ||
− | + | ||
− | + | ||
=== NFRC Ratings === | === NFRC Ratings === | ||
− | The National Fenestration Ratings Council (NFRC) is a non-profit, third-party agency which rates | + | The National Fenestration Ratings Council (NFRC) is a non-profit, third-party agency which rates and labels windows according to their ability to provide thermal insulation and protection from the weather. The NFRC provides these ratings in order to assist consumers compare replacement window performance and identify Energy Star and NFRC-certified windows. |
− | The NFRC rates a window's U-Factor, its solar heat gain coefficient, its visible transmittance, its air leakage and its light to solar gain | + | The NFRC rates a window's U-Factor, its solar heat gain coefficient, its visible transmittance, its air leakage and its light to solar gain. |
=== Energy Star Ratings === | === Energy Star Ratings === | ||
The [[Energy Star Windows|Energy Star]] certification provides assurance that a window is able to limit heat transfer and control the amount of solar gain that enters into a home through the window. Energy Star qualified windows lower energy consumption and reduce greenhouse gas emissions through their ability to control weather penetration and heat transfer. Energy Star windows are certified based on the ratings of the National Fenestration Ratings Council but they do not include all the NFRC's component ratings. | The [[Energy Star Windows|Energy Star]] certification provides assurance that a window is able to limit heat transfer and control the amount of solar gain that enters into a home through the window. Energy Star qualified windows lower energy consumption and reduce greenhouse gas emissions through their ability to control weather penetration and heat transfer. Energy Star windows are certified based on the ratings of the National Fenestration Ratings Council but they do not include all the NFRC's component ratings. | ||
− | Windows which receive the Energy Star label are assessed according to the NFRC's ratings for U-Factor and solar heat gain coefficient | + | Windows which receive the Energy Star label are assessed according to the NFRC's ratings for U-Factor and solar heat gain coefficient. |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | === | + | == Component Ratings == |
− | + | ||
− | + | Replacement window ratings measure the window's energy efficiency according to energy performance characteristics. These characteristics include the U-Factor, the Solar Heat Gain Coefficient, Air Leakage, Light to Solar Gain and Visible Transmittance. | |
− | Replacement window ratings measure the window's energy efficiency according to energy performance characteristics. These characteristics include U-Factor, the Solar Heat Gain Coefficient, Air Leakage, | + | |
=== U-Factor === | === U-Factor === | ||
− | The U-Factor measurement assesses the rate at which a window is able to conduct non-solar heat. This rating represents an entire window's performance including the window's glazing, frame and spacer material. The lower the U-Factor rating, the more energy efficiency the window provides. | + | The U-Factor measurement assesses the rate at which a window is able to conduct non-solar heat. This rating, also called the U-Factor, represents an entire window's performance including the window's glazing, frame and spacer material. The lower the U-Factor rating, the more energy efficiency the window provides. |
=== Center of Glass U-Factor === | === Center of Glass U-Factor === | ||
Line 59: | Line 36: | ||
=== Solar Heat Gain Coefficient === | === Solar Heat Gain Coefficient === | ||
− | The solar heat gain coefficient (SHGF) relates to a percentage of solar radiation which is either absorbed or directly transmitted through a window, and is subsequently released, creating warmth in the room. When less solar heat is transmitted there is greater shading ability which results in a lower solar heat gain coefficient. Windows with high SHGF ratings transmit more solar heat gain during the winter months while windows with a low SHGF rating reduce cooling loads more effectively during the summer months when they block heat from the sun. | + | The solar heat gain coefficient (SHGF) relates to a percentage of solar radiation which is either absorbed or directly transmitted through a window, and is subsequently released, creating warmth in the room. When less solar heat is transmitted there is greater shading ability which results in a lower solar heat gain coefficient. Windows with high SHGF ratings transmit more solar heat gain during the winter months while windows with a low SHGF rating reduce cooling loads more effectively during the summer months when they block heat from the sun. The need for a high or low SHGF is dependent on the climate in which the windows are to be installed. |
=== Air Leakage === | === Air Leakage === | ||
− | + | The rate that air infiltrates into a room from the area that surrounds a window is the window's Air Leakage rating. Window spacers, sealants and other weatherstripping products impact on a window's air leakage. A low air leakage rating indicates that the window has a low percentage of air leakage. | |
=== Light-to-Solar Gain === | === Light-to-Solar Gain === | ||
− | Light-to-Solar Gain (LSG) | + | The rating for Light-to-Solar Gain (LSG) indicates the ratio between the visible transmittance and the solar heat gain coefficient. The measurement for light to solar gain assesses the relative efficiency of different types of glazing as daylight is transmitted to gauge how well the glass blocks heat gains. A high LSG rating will indicate that a higher ratio of light is transmitted without significantly adding higher amounts of heat. |
=== Visible Transmittance === | === Visible Transmittance === |